The ongoing devaluation of the U.S. dollar and the large and persistent trade deficits of the U.S. current account are a threat to the American supremacy. Consequences of such unbalances afflict worldwide economy and are subject of international concerns. This publication studies the relationship of the challenged U.S. dollar to its new competitors. The comparative analysis starts with a description of the actual International Monetary System (IMS). A review of the determinants for the internationalization of a currency is then provided. Furthermore, the potential of several currencies as well as the U.S. dollar is assessed using internationalization determinants. A description of how economies of scale, self-supply, monopoly, dependence and historical inertia reinforce the dominant currency’s leadership, is also included. Finally, an outlook on the future of the IMS is provided by presenting three possible scenarios: the status quo, a Finance G-2, and a multipolar world. Throughout this approach, this publication provides answers to the future of the pre-eminence of the U.S. dollar against its competitors, in particular against the Euro and the Yuan.